Conventionally, for a drive device having a motor, a drive device casing which stores the motor, and an inverter which controls the motor, a structure is proposed having a cooling structure for cooling the inverter and the motor.
FIGS. 6, 7, and 8 show a cooler structure of a related art disclosed in Patent Literature 1 described below. FIG. 6 is an overall perspective view of the cooling structure, FIG. 7 is a vertical cross sectional diagram of the cooling structure, and FIG. 8 is a vertical cross sectional diagram of primary portions of the cooling structure. Heat discharged by a heat discharging structure such as an inverter 3 and a motor 1 is discharged to a coolant which circulates in a coolant circulation path 4 between the heat discharging structure and a radiator 42, to thermally protect the heat discharging structure.
The inverter 4 comprises a switching transistor which converts a direct current power of a battery power supply into an alternating current power and associated circuit elements, and a circuit board on which the switching transistor and the circuit elements are placed. The inverter 3 is mounted on an upper surface side of the board itself or a heat sink 53 integrated with the board by attaching a separate member on the board, and the heat sink 53 is fixed on a bottom portion of an inverter casing 7 which stores the inverter 3. A lower surface of the heat sink 53 is formed as a heat discharging surface 53a thermally connected with the inverter 3. The inverter casing 7 is formed to cover and protect the inverter 3 placed therein from rainwater and dust.
The motor 1 is stored in the drive device casing 2, and a spacer member 6 is provided on an upper surface of the drive device casing 2. An opposing surface 6a which is placed opposing the heat discharging surface 53a and which is thermally connected with the motor 1 is formed on an upper surface of the spacer member 6. On the upper surface of the spacer element 6, a rectangular recess is formed for forming a coolant space R between the upper surface of the spacer member 6 and the lower surface of the heat sink 53, that is, the heat discharging surface 53a, in a state where the heat sink 53 is mounted on the spacer member 6. A bottom surface of the recess forms the opposing surface 6a. On a lower surface of the spacer member 6, a recess 61 which cooperates with the upper surface of the drive device casing 2 to form an inflow-side coolant path Ri and a recess 62 which cooperates with the upper surface of the drive device casing 2 to form an outflow-side coolant path Ro are formed parallel to each other.
The cooling structure is formed by forming a coolant space R between the heat discharging surface 53a of the heat sink 53 and the opposing surface 6a of the spacer member 6, providing a plurality of heat discharge fins 56 placed in a standing manner and parallel to each other in the coolant space R from the heat discharging surface 53a toward the opposing surface 6a, and forming an inter-fin passage Rp through which coolant flows between adjacent ones of the plurality of heat discharge fins 56. The heat discharge fin 56 extends in the coolant space R from the heat discharging surface 53a on the side of the heat sink 53 toward the opposing surface 6a of the spacer member 6, in order to retain a heat exchange area, and laterally crosses across the coolant space R in its thickness direction.
The heat discharge fin 56 is formed by machining a lower side of the heat sink 53, and the heat discharging surface 53a is formed close to the side of the inverter 3. In the placement of the fin 56 in standing manner, a length of a tip of the heat discharge fin 56 is set shorter than a length of the base end in relation to a site where the fin 56 is placed in a standing manner from a surface before the machining, and an end surface of the inter-fin passage Rp is inclined with respect to the direction of standing of the heat discharge fin 56.
With the recess 61 of the spacer member 6 and the upper surface of the drive device casing 2, the inflow-side coolant reservoir Ri is formed extending in a lined direction of the inter-fin passage Rp, and with the recess 62 of the spacer member 6 and the upper surface of the drive device casing 2, the outflow-side coolant reservoir Ro is formed extending in the lined direction of the inter-fin passage Rp. The inflow-side coolant reservoir Ri and one end of the inter-fin passage Rp are connected and coupled by a diaphragm portion Rs extending in a lined region of the inter-fin passage Rp, and the outflow-side coolant reservoir Ro and the other end of the inter-fin passage Rp are connected and coupled by a diaphragm portion Rs extending in the lined region of the inter-fin passage Rp.
On positions of the drive device casing 2 opposing the recesses 61 and 62, fins 21 are provided in a standing manner toward the inflow-side coolant reservoir Ri and the outflow-side coolant reservoir Ro, to increase a heat transfer area.
On a side end of one side of the spacer member 6, an inflow-side port 51 for allowing coolant to flow into the inflow-side coolant reservoir Ri and an outflow-side port 52 for allowing the coolant to flow out from the outflow-side coolant reservoir Ro are connected parallel to each other. With a coolant pump 41 provided in the coolant circulation path, the coolant supplied to the inflow-side coolant reservoir Ri is passed through the plurality of inter-fin passages Rp placed parallel to each other through the diaphragm portion Rs, to cool the inverter 3 through the heat discharging surface 53a. The coolant after the cooling of the inverter 3 flows out to the outflow-side coolant reservoir Ro through the diaphragm portion Rs.